The present invention relates to a facsimile, and particularly to a facsimile which facilitates paper conveyance and has a simplified structure and an improved white level controller so as to accomplish uniform picture quality.
Generally, a facsimile has a white level controller for determining the relative brightness of a source document by reflecting light projected from a reading device back to the reading device before the source document is actually read.
Such a conventional white level controller for a facsimile, as schematically shown in FIG. 1, is constructed to comprise a white rubber roller 4 installed to be resiliently in contact with a glass 3 by a spring 5 on glass plate 3 installed on the top of a reading device 1 to facilitate conveying source document 2 along upper and lower guide plates 8 and 9, or, as in FIG. 2, to comprise a white plate 7 installed to be resiliently in contact with spring 6 on glass plate 3.
In the first case, wherein the white rubber roller of FIG. 1 is used, the white level controller for a facsimile has a complicated structure because the white rubber roller requires some means to power its rotation. Further, since the overall surface of the white rubber roller comes in contact with the glass when being rotated, if foreign matter is introduced to one or both of these surfaces, the glass may be damaged and the picture quality thus deteriorated, which also adversely affects proper maintenance.
In the other case, wherein the white plate of FIG. 2 is used, since the compression force of the spring is non-uniform, the source document conveyance is not smooth and paper jams occur.